Anyone
who has looked out at the sky on a clear night has wondered: With
so many stars out there, are we alone? What is out there and from
where do we come?

Astronomers,
perhaps more than anyone, have wondered too. They've helped
engineer the observatories that make the stars appear closer.
Still, with each advance of the telescope, from Galileo's
simple invention in 1609, to the Hubble Space Telescope in recent
years, astronomers have found more questions than answers. And
they have yet to locate terrestrial planets outside of our solar
system.

When
he was a young boy in suburban Chicago, Steven Majewski daydreamed
about galaxies, which he drew pictures of in the margins of his
textbooks. His parents later took him to Cape Kennedy to see the
Apollo 11 launch.

"I
couldn't believe it," said Majewski, an associate professor
of astronomy, who
joined the faculty in 1995. "I thought, 'people get to explore
space for a job?' That's when I knew I would make a career studying
the stars."

Majewski
and other U.Va. astronomers soon will be working on a tool that
may bring the indicators of other Earth-like planets into view.
NASA's Space Interferometry Mission, a space telescope to
be launched by a rocket in June 2009, will provide new insights
about the origin and evolution of planets, stars and galaxies
like the Milky Way. With the capability to measure distances and
angles more precisely than ever before, SIM will survey the stars
in our galaxy to provide answers to such fundamental questions
as: What is the distance of our sun from the center of the Milky
Way? How much does our galaxy weigh? Ultimately, this mission
should provide a key step to the discovery of other planets that
may support life.

FAME
Tracks the Stars

While
NASA's Space Interferometry Mission (SIM) is a highly
accurate targeted telescope, allowing astronomers to pick
out key selected star groups to study, there also is a need
for telescopes that can survey the sky, providing a broad
sweep to help astronomers narrow their search for particular
stars of interest, especially the ones that may have orbiting
planets.

Much
of this survey work will be done by FAME  the Full-sky
Astrometric Mapping Explorer, a satellite telescope to be
launched by NASA in 2004.

"FAME
will provide the most accurate catalog of star positions
in history," says Kenneth Seidelmann, chair of the
FAME science team.

eidelmann
came to U.Va. last fall as a professor of astronomy after
retiring from a career at the U.S. Naval Observatory in
Washington, D.C.

Astrometry,
the science of determining the positions of stars, is the
oldest branch of astronomy and has been a focus area at
U.Va. for 100 years. Seidelmann, with the help of several
U.Va. astronomers, will use a portion of FAME's five-year
mission time to help SIM astronomers locate stars for further
study when their mission goes into operation.

"FAME
will help us look for nonlinear movement of stars, the ones
with ragged motions, possibly indicating the presence of
an orbiting body," Seidelmann says. "Those are
some of the stars SIM will later detail."

"SIM
will be the most advanced space telescope yet, equivalent to four
times the size of Hubble and a thousand times more refined in
terms of showing fine detail," said Majewski, a team leader
for a major SIM project to measure the Milky Way.

The
optical detail of the SIM telescope, operating far outside the
distorting affects of the Earth's atmosphere, should allow
us to observe indicators of Earth-sized planets orbiting nearby
stars." SIM's ability to resolve detail is so fine,
it's equivalent to reading a newspaper headline on the moon
from Earth, he said.
SIM will be directed to a position 59 million miles from Earth
where it will trail our planet in its orbit around the Sun. SIM
will gather light from multiple on-board telescopes working together
for a combined effect, allowing the instrument to provide images
with the sharp, precise clarity of a single large telescope. It
is a clever, complex design, pioneered in 1907 by physicist Albert
Michelson, making it possible to, in effect, deploy a huge observatory
as a rocket payload.

"U.Va.'s
involvement with SIM includes the important preliminary work of
setting up the fundamental reference system of stars  a
pre-launch grid of comparison positions in the galaxy, and then
using SIM to do a key project, measuring the mass of the Milky
Way galaxy," Majewski said. "We still do not know this
fundamental astrophysical quantity because of the presence of
an unknown amount of the mysterious dark matter. Our experiment
will undertake the first study of the motions of distant stars
to determine the gravitational forces that cause these motions,
and this will help us better understand the amount and distribution
of matter in the Milky Way."

Dark
matter, its existence or nonexistence, is one of the great mysteries
of astronomy, he said. Believed to be composed of exotic subatomic
particles, extremely dark stars or black holes, dark matter may
make up as much as 90 percent of the universe's mass.

"There
may be much more matter t†hat we cannot see than matter that we
do see," said Majewski, who, before coming to U.Va., was
a Hubble and Carnegie Institution fellow in Pasadena, home site
of the SIM project at NASA's Jet Propulsion Lab. "But
although it is presently invisible to our telescopes, we can see
the effects of dark matter, its gravitational pull on visible
objects. SIM will help us to measure these effects, thereby allowing
us to measure how this dark matter is distributed in our own galaxy.
This will provide an important clue to the amount and nature of
the dark matter. Knowing this, in turn, could tell us a great
deal about the creation of the universe and its evolution."

SIM
is a $932 million mission, part of NASA's Origins Program,
a series of missions to answer the fundamental questions of how
we got here and if there is other life out in space. Majewski
is one of 10 principal investigators leading key science teams.
Majewski's team, which includes U.Va. research scientist
Richard Patterson and other U.Va. astronomers, as well as 10 researchers
at seven other institutions, will be funded by NASA as a multi-million-dollar
research effort over the next decade. Majewski's U.Va. group
already has received $650,000 to provide NASA with the SIM reference
grid. Philip Ianna, U.Va. professor of astronomy, is a member
of another key SIM science team, whose goal is to obtain precise,
fundamental measurements of the masses and luminosities of stars.

Through
these two key projects, U.Va. astronomers will have access to
10 percent of the viewing time with the SIM telescope, a significant
portion of the observational budget during the five-year mission.

Though
it will be years before SIM is launched, Majewski says he is excited
in his preparation for the endeavor.

"The
process of discovery is what makes research interesting,"
he said. "The fun is not just in finding the answers, but
also in seeking clear ways to discover the answers to our most
timeless questions."